The Three Stages Of Seyle's General Adaptation Syndrome

EndurElite Chief Endurance Officer Matt Mosman discusses General Adaptation Syndrome and how the body responds to the stress of endurance exercise.

Seyle's General Adaptation Syndrome Simply Explained

Woo wee! Excuse me, EndurElite family of fast. This marathon training has been giving me some major, major GAS. Well, maybe that in the combination of Fibersol for my 40-year-old bowels, but all juvenile antics aside, GAS isn't what you think it is in this video today.

General Adaptation Syndrome (GAS) Definition

GAS stands for general adaptation syndrome, and this theory was first proposed by a Canadian endocrinologist and biologist named Hans Selye.

And basically, Hans Selye went to the scientific community and he said: "I'm gonna pump you up with how the body responds to exercise when new stress is put on it or when more intense stress put on it, and kind of the three phases the body goes through."

So, today, we're gonna talk about GAS, general adaptation syndrome. And like I said before when the body experiences a new stress such as endurance exercise or greater stress put on it than previously applied, it goes through different phases.

The phases of GAS are:

  • Alarm
  • Resistance
  • Exhaustion

So let's briefly describe what each one is and then we'll put it into an example of marathon training, and then we'll wrap it all up in a nice little neat package for you.

General Adaptation Syndrome Stages

Stage 1: Alarm

So, the first phase of GAS is the alarm phase and this is basically when your body is getting used to the exercise.

And during this phase, it may last, you know, several days to several weeks and you may experience excessive soreness, stiffness, you may experience a drop in performance, and this is mostly due to the release of cortisol as this new stresses applied in your body adapting to it.

So that is the alarm phase.

Stage 2: Resistance

The next phase is the resistance phase and during this phase is where your body really starts to adapt to the exercise, you return in normal function, and you don't experience that stiffness or soreness quite as much and you can bounce back quicker.

Now, a lot of the changes that are happening here are on a neurological level, which allows the endurance athlete to keep on training, and at the same time, the muscles making adaptations too to this new stress.

So, you know, maybe increase in mitochondrial density, capillary density, the musculature itself is adapting to this new stress you're putting on it.

And the athlete can remain in this resistance phase for quite some time depending on how conditioned the athlete is and if they're recovering.

But if they go too long in this resistance phase, then they move onto the exhaustion phase.

Stage 3: Exhaustion

In the exhaustion phase, a lot of things happen that are similar to the first alarm phase and that you may experience some more stiffness or soreness.

You may not be able to recover quite as fast, you may not be sleeping, a lot of signs of overtraining may start to present themselves.

So, the exhaustion phase is something we want to avoid, so as we go through that resistance phase and we kind of peak for an event, after that, we kind of want to take a little break so we basically avoid that exhaustion phase altogether.

An Example Of General Adaptation Syndrome

So, those are the three phases of Hans Selye's general adaptation syndrome.

Now, let's put this into an example real quick. So, I'm training for a marathon right now and, you know, I first started out like "Oh, this is great, this is great, this is great what the..."and I hit the alarm phase.

And my performance just decreased. I was sore, I was stiff, and I just feel like I couldn't recover. If you watch some of those videos, you know exactly what I'm talking about.

And then about two weeks later, I start to feel better and better and like "Yeah, I'm a badass now. My body knows how to do this perfectly."

So that would be the resistance phase and then as I kind of keep on building up to this marathon on June 3rd, my body is gonna get stronger and adapt better to the exercise, and then I'll kind of hit a plateau.

I'll do the marathon, and then I'm gonna wanna take a break, so I avoid the exhaustion phase

So, if you were to put GAS into, like, a chart, it would look something like this:

  • You start out straight
  • The alarm phase you dip down
  • Your resistance phase you start going back up adapting to the exercise, then it kind of levels off where you're plateauing
  • And then if you go too far and you reach the exhaustion phase, it'll start to drop off like this.
Hans Seyle's General Adaptation Syndrome

    So straight, drop, resistance, plateau, exhaustion. So that is GAS in a nutshell, general adaptation syndrome.

    Now, if you have a lot of GAS, it's perfectly okay as long as you avoid that exhaustion phase at the end.

    You know, the body is pretty amazing adapting to exercise, but just like anything, it takes time for, you know, the body to respond to the stress, to put on it and to become stronger.

    So that is about it for today, my endurance friends. If you like this video or have GAS of your own, share this with your friends. If you wanna see other videos like this, head over to the EndurElite YouTube channel or the EndurElite website at And until next time, my endurance friends. Stay fueled, stay focused, and stay fast.